There are a number of exercise devices that operate to allow a user to implement a foot action following a generally closed, curved path of travel, simulating running and/or walking. These devices are generally referred to as “elliptical” exercise devices. Many such elliptical exercise devices are large, complicated, costly, and/or have undesirable characteristics related to the motion of the user's feet.
U.S. Pat. No. 5,518,473 to Miller shows an early design for an elliptical exercise device. The device provides a path of travel that simulates running and/or walking but is quite large and does not provide for arm exercise.
U.S. Pat. No. 5,611,756 to Miller discloses an elliptical exercise device with arm and leg movement. A pair of guide links are pivotally supported on a frame and a foot engaging link is supported at the lower end of each guide link. An intermediate link connects each guide link to crank. A control link joins each foot link to the corresponding intermediate link to vary the angle of the foot link relative to the guide link.
U.S. Pat. No. 6,045,487 to Miller discloses an elliptical exercise device having a pair of guide links pivotally supported on a frame and a foot link supported at the lower end of each guide link. An intermediate link connects each guide link to a crank of a crank system. A flexible control member engages each foot link and extends up and over a pulley located at the guide link pivot axis. The control members connect to a reciprocating assembly for moving the foot links up and down as the guide links pivot back and forth.
U.S. Pat. No. 7,708,668 to Rodgers, Jr. shows several embodiments of an exercise device having flexible elements coupling left and right foot support members to a crank system. The exercise device allows for a variable stride length and decouples the vertical and horizontal components of foot travel.
U.S. Pat. No. 7,556,591 to Chuang et al. discloses an exercise device with cranks mounted to an upper portion of a frame. Two handles are pivoted to the frame forward of the cranks. Foot supports are pivotally coupled to the lower ends of the handles. Pivot rods extend between each foot support and one of the cranks. Additional links connect each handle with the same cranks as the respective pivot rod.